DE69612848T2 - BIODEGRADABLE ALKYLENE OXYD LAKTON COPOLYMER - Google Patents

Abstract

The biodegradability of polyglycol-based block copolymers is improved by including in the copolymer a lactone. Representative of these biodegradable enhanced copolymers are those made of 1,2-butylene oxide and epsilon -caprolactone capped with a homopolymer block of ethylene oxide. The copolymers of this invention have many uses, such as nonionic surfactants, foam control agents, lubricants, and the like.

Description

1-2 Nov 2000

European Patent Application

No. 96 913 828.8

The Dow Chemical Company

23379P DEU/BBDH

This invention relates to biodegradable random copolymers of one or more lactones and one or more alkylene oxides capped with an alkylene oxide block comprising the same or one or more different alkylene oxides as those used to prepare the copolymer. Another aspect of the invention relates to processes for preparing the alkylene oxide-lactone copolymers and the use of these copolymers as nonionic surfactants and foam control agents.

Polyoxyalkylene block copolymers and homopolymers, also known as polyalkylene oxide block copolymers and homopolymers, are widely used as nonionic surfactants, foam control agents, mineral wetting agents, surfactants for use in cleaning formulations, emulsifiers, de-emulsifiers, dispersants, synthetic lubricants and for any application where surface active properties, lubricity or foam control are important. In particular, polyoxyalkylene copolymers of propylene oxide (PO), the butylene oxides, especially 1,2-butylene oxide (BO) and ethylene oxide (EO) represent an important class of such materials.

In general, the hydrophilic portion of nonionic surfactants and foam control agents is typically a polyoxyethylene (POE) group. The hydrophobic block can be derived from a wider set of possible materials, examples of which include alkylated phenols, fatty alcohols and fatty acids, polyoxypropylene (POP) and polyoxybutylene (POB). Each hydrophobic group imparts unique performance characteristics to the nonionic surfactant or foam control agent of which it is a part.

Polyglycol-type block copolymers generally exhibit a high degree of resistance to biodegradation. In general, however, polyglycols will eventually biodegrade over time, but not within the time period specified in most standardized tests.

Copolymers of alkylene oxides and lactones are known, see for example US patents 2,962,524; 3,312,753; 3,689,531 and 4,291,155, however these copolymers are not capped, and many are prepared with monofunctional initiators.

The invention provides biodegradable alkylene oxide-lactone block copolymers, the block copolymers comprising a first block comprising polymerized units of one or more alkylene oxides and one or more lactones, and a second block comprising polymerized units of one or more alkylene oxides (which may be the same or different as those used to prepare the first block). The presence of a lactone in the first block introduces ester functionalities into the copolymer, which

in turn enhances the overall biodegradability of the copolymer. In addition, this ester functionality in combination with the polyalkylene oxide cap, i.e. the second block, gives these copolymers a design flexibility that allows each to be tailored to specific applications, for example, it allows simple changes in the copolymer structure, which in turn affect the solubility properties, foam control properties, etc. of the copolymer and thus also the application in which the polymers can be used.

Figure 1 shows general structures for two butylene oxide/e-caprolactone/ethylene oxide-&ogr; copolymers (also often called copolyesters) and two commercial butylene oxide/ethylene oxide copolymers (polyglycol B40-1900 and BL50-1500, both manufactured by DowChemical Company).

Figure 2 is a diagram of a biodegradation test of a surfactant of this invention and a commercially available surfactant (polyglycol BL50-1500)

>15

,Figure 3 is a bar graph showing the results of a foam control mixer test per ASTM D3519-88 using 0.01% sodium dodecyl sulfate as the foaming agent.

Figure 4 is a bar graph showing the results of an ASTM D3519-88 mixer test using a mixture of 0.2% egg albumin and DOWANOL® PM glycol ether as a foaming agent.

Figure 5 is a graph illustrating biochemical oxygen demand (BOD) tests of a control substance and a foam control agent of this invention using bacterial pathogens from a municipal source.

Figure 6 is a graph illustrating BOD testing of a control and a foam control agent of this invention using bacterial pathogens from an industrial source.

The base copolymer or first block of the alkylene oxide-lactone copolymers of this invention and their methods of preparation are fully described in U.S. Patents 2,962,524; 3,312,753; 3,689,531 and 4,291,155. The recurrence of the alkylene oxide and lactone groups within the copolymer backbone is typically random, but may contain certain degrees of block character.

The alkylene oxide components of the base copolymer include those of formula I

R R

40

HCCH ^(I)

wherein each R is independently hydrogen, C ₁ -C ₆ -alkyl or haloalkyl, or wherein

the two R substituents together with both vicinal epoxy carbons form a saturated or monoethylenically unsaturated cycloaliphatic hydrocarbon ring, preferably of five or six carbon atoms. The preferred alkylene oxide monomers contain from 2 to 12 carbon atoms and representative alkylene oxide monomers include ethylene oxide, propylene oxide, the butylene oxides, 1,2-epoxydodecane, cyclopentene oxide, cyclohexene oxide, styrene oxide and epichlorohydrin. The butylene oxides, particularly 1,2-butylene oxide and propylene oxide are the more preferred alkylene oxide monomers. Although the alkylene oxide component may comprise two or more different alkylene oxides, for example a mixture of ethylene and propylene oxides, it typically and preferably consists of a single alkylene oxide.

The lactone used in this invention can be any lactone or combinations of lactones having at least four carbon atoms in the ring, and these lactones include those of formula II

MR'

I!

R' - c (~c-) _n - c = &ogr;

ⁿ (U)

^R1

Q

wherein when η is at least one, each R' is independently hydrogen, with the proviso that when π is 2, at least four R' are hydrogen and when η is more than 2, the remaining R' are hydrogen, alkyl, cycloalkyl, alkoxy or single ring aromatic hydrocarbon radicals.

The lactones preferred as starting materials for the copolymer or first block of this invention include unsubstituted ε-caprolactones, ε-caprolactones substituted at the carbon atom in the ring with one, two or three lower (one to four carbon atoms) alkyl radicals, and unsubstituted δ-valerolactones and γ-butyrolactones. The preparation of unsubstituted lactones is well known. The substituted δ-caprolactones and mixtures of such lactones can be prepared simply by reacting an appropriately substituted cyclohexanone with an oxidizing agent such as peracetic acid. The cyclohexanones can be obtained from substituted phenols or according to other suitable synthetic methods. Other lactones suitable as starting materials include alkoxy-e-caprolactones such as methoxy- and ethoxy-c-caprolactone, cycloalkyl-, aryl- and aralkyl-s-caprolactones such as cyclohexyl-, phenyl- and benzyl-s-caprolactone, and lactones such as σ-enantholactone and η-caprylactone, which have more than six carbon atoms in the ring.

The ε-caprolactones are the preferred lactones for preparing the copolymer or the first block of this invention and these include those of formula III

C O

(R") ₂ — C _C _ _(R ,, ₎₂

^

wherein each R" is independently hydrogen or a C ₁ -C ₄ -alkyl or alkoxy group, with the proviso that no more than three R" substituents are groups other than hydrogen. Preferably, all R" substituents are hydrogen. Unsubstituted ε-caprolactone is the preferred ε-caprolactone.

The copolymer is prepared by polymerizing the alkylene oxide and lactone monomers with each other and a catalyzed initiator. In this process, the growth of the polymer molecule is due to the attachment of linear (ring-opened) lactone units and alkylene oxide units to the functional sites of the initiator. The initiator can be mono- or poly- (e.g., di-, tri-, tetra-, etc.) functional, the functional site(s) typically being a reactive hydrogen. Exemplary initiators include alcohols, amines, mercaptans, phenols, amino alcohols, and mercapto alcohols. The hydroxyl and amino terminated initiators are preferred.

The monohydroxy initiators used in this invention are represented by the formula IV

R'"(OR ^iv ) _a OH (IV)

exemplified, wherein R'" is a hydrocarbyl, such as alkyl, cycloalkyl, aryl, aralkyl, alkaryl, etc., preferably containing up to 18 carbon atoms; R' ^v is an alkylene radical, preferably containing two to four carbon atoms; and a is an integer having a value of 0 to 18, preferably a value of 0 to 2. Exemplary monohydroxyl initiators include the alkanols, for example methanol, ethanol, isopropanol, n-butanol, 2-ethylhexanoi and dodecanol; the monoalkyl ethers of glycols and polyglycols, for example 2-ethoxyethanol, 2-propoxyethanol, 2-butoxyethanol, the monoethyl ethers of diethylene glycol, of triethylene glycol, of tripropylene glycol; the monopropyl ethers of polyethylene glycol, of polypropylene glycol, of polybutylene glycol; and the alkylene oxide adducts of substituted and unsubstituted phenols, for example the ethylene oxide and/or propylene oxide adducts of alkylphenols such as nonylphenol.

The polyfunctional compounds are those with at least two reactive hydrogens that are capable of opening a lactone ring or a vicinal epoxide ring. These compounds include those of formula (V)

R ^V (YH) ₂ (V)

wherein R ^v is an aliphatic, cycloaliphatic, aromatic or heterocyclic radical; ζ is at least two; and the Y's are -O-, -S-, -NH- or NR ^vi -, wherein R ^vi is an alkyl, aryl, aralkyl or cycloalkyl radical. Diols, polyols, diamines are the preferred polyfunctional initiators and these include ethylene and propylene glycol, diethylene and dipropylene glycol, 1,2-dibutylene glycol, glycerin, trimethylolpropane, pentaerythritol, ethylenediamine and ethanolamine.

Any catalyst that promotes the polymerization of the alkylene oxide and lactone monomers can be used to practice this invention. Representative catalysts include alkali metal and alkaline earth hydroxides and Lewis acids. Preferred catalysts are the alkali metal hydroxides, particularly potassium hydroxide (KOH).

The catalyst is used in catalytically significant amounts, which is a function of many variables, including the nature and amounts of reactants, temperature, and mixture. Catalyst concentrations of 0.001 to 2 wt.% are typical, with a concentration of 0.01 to 1 wt.% being preferred.

The base copolymers of this invention are prepared using conventional equipment and techniques. Typically, the lactone(s), e.g. 5-caprolactone, and the alkylene oxide(s), e.g. 1,2-butylene oxide, monomers are charged as a mixture (the relative amounts of each substance may vary as desired) in the presence of a catalytic amount of one or more alkali metal hydroxides, e.g. potassium hydroxide, to a reactor containing an organic initiator, e.g. either a mono- or polyfunctional initiator such as 2-ethylhexanol or glycerin if the copolymer is to be capped, or a polyfunctional initiator if the copolymer is to be left uncapped. The polymerization reaction is generally carried out at a temperature between 75 and 175°C, preferably between 85 and 150 ^° C, and under anhydrous conditions. It may be carried out batchwise, semi-continuously or continuously.

The copolymer is capped with an alkylene oxide (which may be the same, but preferably different from the alkylene oxide(s) used to form the copolymer) to give a polymer block cap. The initiator used to form the copolymer may be either mono- or polyfunctional.

The polymer block resulting from the capping step consists of a homopolymer if a single monomer is used or a copolymer if more than one monomer is used. The amount of alkylene oxide used to cap the first block can vary widely. Exemplary alkylene oxide capped copolymers include (BO/lactone)-EO and (PO/lactone)-EO copolymers having a hydrophobic group with a molecular weight greater than 300 with a final EO weight percent of greater than 0 and up to 90. Preferred hydrophobic embodiments include a BO/lactone or PO/lactone having a molecular weight of 750 to 2000 with EO between 20 and 80 weight percent in the capped copolymer.

The temperature and other reaction conditions under which the capping reaction occurs are essentially the same as those used for the copolymerization reaction of the alkylene oxide and the lactone. Typically, after the copolymerization reaction is complete, the capping alkylene oxide is fed into the same reactor and in the same manner as the starting copolymer. After the reaction is complete, the alkali metal hydroxide catalyst is neutralized and the capped polyoxyalkylene product recovered using conventional equipment and techniques. For copolymers of ε-caprolactone and 1,2-butylene oxide, the preferred capping alkylene oxide is ethylene oxide.

The capped polyoxyalkylene copolymers of this invention are useful as nonionic surfactants and foam control agents, among others. These block copolymers are used in the same way as known surfactants and as foam control agents, but they show increased biodegradability compared to polyoxyalkylene copolymers that do not have a polymerized lactone group in their

is backbone, for example polyoxypropylene, polyoxybutylene, etc. Furthermore, the capped polyoxyalkylene block copolymers of this invention have increased design flexibility compared to uncapped copolymers due to the combination of the capping block and the presence of polymerized lactone groups in the polymer backbone.

The following examples describe this invention in more detail. Unless otherwise indicated, all parts and percentages are by weight.

METHODOLOGY

Both the ε-caprolactone (ε-CL) and n-dodecane used in these examples were purchased from Aldrich Chemical Company, Inc.

Process for synthesizing a surfactant from βΩ/ε-CL-EO copolymer
. 200 g of 1,2-propylene glycol monobutyl ether and 4 g of solid KOH were added to a closed system, namely a 2 gallon steel reaction vessel. The reactor was sealed and the temperature raised to 130 ^° C, at which time a mixture of 518 g of 1,2-butylene oxide and 519 g of ε-CL was added at a rate such that the internal pressure was maintained at less than 70 pounds per square inch absolute ("PSIA") (483 kPa absolute). After all of the 1,2-butylene oxide/caprolactone mixture was added, the temperature of the reaction mixture was maintained at 130 ^° C until the pressure drop was less than 0.5 PSIA over a one hour period.

After the digestion period was completed, the reactor contents were sampled and a percent hydroxyl analysis was performed to determine the average molecular weight of the hydrophobic product (surfactant). The analysis showed that the monol polymer had a hydroxyl equivalent weight of 727 (corresponding to a number average molecular weight of 727).

To provide the material for hydroxyl analysis sampling, 396 g of the hydrophobic monol intermediate was taken. To the remaining 845 g of intermediate monol

1080 g of ethylene oxide was added, followed by a digestion period similar to above. A total of 424 g of the mixture was sampled and analysis showed that the product had a hydroxyl equivalent weight of 1453 (corresponding to a number average molecular weight of 1453). The final liquid surfactant product (1501 g) was neutralized with 2.22 g of glacial acetic acid.

Process for the synthesis of foam control agents from &Rgr;&Ogr;/&egr;-CL

96 g of 1,2-propylene glycol and 4.75 g of solid KOH were placed in a closed system, namely a 2 gallon steel reaction vessel. The reactor was sealed and the temperature was raised to 120°C, at which time 1375 g of propylene oxide and 1375 g of ε-CL (50/50 w/w) were added at such a rate that the internal pressure was maintained at less than 70 PSIA (483 kPa absolute). After this addition of all of the propylene oxide/caprolactone

> mixture, the temperature of the reaction mixture was maintained at 120 ⁰ C until the pressure drop was less than 0.5 PSIA over a one hour period.

After the digestion period was completed, the reactor contents were sampled and a percent hydroxyl analysis was performed to determine the average molecular weight of the product. The analysis showed that the diol copolymer had a hydroxyl equivalent weight of 942.5 (corresponding to a number average molecular weight of 1885).

To provide the material for hydroxyl analysis sampling, 245 g of the diol product was withdrawn, leaving 2606 g of product. The final liquid product was neutralized by hot filtration through a magnesium silicate filter cake.

The above procedure was repeated to prepare 80/20 (w/w) �RΩ/ε-CL foam control agents using the required amounts of PO and ε-CL

Surfactants comprising (BO/lactone)-EO copolymer having hydrophobic groups of M _w greater than 300 capped with EO to give a final EO weight percent of between 0 and 90% are preferred. This is also true for (PO/lactone)-EO copolymers. The most preferred hydrophobic embodiment comprises a hydrophobic group comprising BO/lactone or PO/lactone of 750 to 2000 M w and capped with EO to give a final percentage of EO in the polymer of between 20 and 80%.

The preferred molecular weight range of BO/lactone or PO/lactone polymers is higher than 300 Mw.

The preferred ratio range of oxide to lactone is between 99/1 and 1/99.

Examples of lactone-type monomers suitable for this invention include epsilon-caprolactone, alkyl-substituted epsilon-caprolactones, delta-valerolactone, and gamma-butyrolactone.

Percent hydroxyl (OH) analysis to obtain number average molecular weights was performed using test methods according to ASTM D4274-88, Method D with the modification that the endpoints were detected by potentiometry.

The method for obtaining the drapes wetting time was ASTM D2281-68. The drapes were purchased from Testfabrics, Inc. and a 3 g copper hook was used.

For Ross Miles foam testing, ASTM method D1173-53 was used. The temperature was maintained at 25 and 5O ⁰ C using a temperature control bath.

To determine the cloud point, approximately 80 mL of a 1% (w/v) solution of surfactant was added to a 100 mL vessel containing a magnetic stirrer. The solution was placed on a heating/stirring unit. A red alcohol thermometer

k ball was completely immersed in the solution and secured to a ring stand by means of a small clamp. The stirrer was started and the heat control was gradually increased to give a solution temperature rise of about 2 ⁰ C per minute. Two observations were made: (1) the temperature at which the solution could be seen with the naked eye to become cloudy and (2) the temperature at which the turbidity completely obscured the red thermometer bulb. Cloud points close to 25°C or even lower were achieved by first cooling the solution to 5°C and then slowly warming it back up.

To measure all surface and interfacial tensions, a computer-automated Krüss Model K-12 voltmeter (Krüss USA) was used.

Interfacial tensions were performed under dodecane. Ancillary equipment included a Lauda RM-6 constant temperature circulating bath which maintained the temperature at 25 ± 0.1 ⁰ C. A Methrom Model 665 Dosimat automatic pipette dispenser was used to add precise increments of the surfactant stock solution to the measuring vessel for CMC (Critical Micelle Concentration) work. A logarithmic dosing method was used. Interfaces were not aged in any way other than the time required for the instrument to make its measurements.

Biodegradability tests

For the closed bottle BOD test, the standard EPA protocol was used (Standard methods for the Examination of Water and Waste Water, 15th edition, American Public Health Association, American Water Works Association, and Water Pollution Control Federation, 1980), with measured oxygen consumption performed using an oxygen-selective electrode. BOD is defined as the weight of oxygen taken up per unit weight of test material. Bacterial microbes were obtained from both industrial and municipal sources.

Figure 1 shows general structures of two βΩ/ε-CL/EO copolymers and two BO/EO products of commercial origin. Example 1 is a diol triblock copolymer prepared using a polybutylene glycol initiator with a nominal molecular weight (M _n ) of 250

in number average and by adding a mixture of 25 wt% ε-CL in BO to give a diol with a M _n of 730 (17 wt% ε-CL in the final intermediate). This intermediate was then reacted with EO to give a triblock surfactant of 1878 M _n .

The second material (Example 2) was prepared by initiating with DOWANOL® PnB glycol ether (propylene glycol mono-n-butyl ether, manufactured by Dow Chemical Company) and feeding at a 50/50 (w/w) ratio of β�O/ε-CL to 727 M _n , and then capping with EO to 1453 M _n .

Table 1 shows the wetting, foaming and cloud point properties for the βΩ/ε-CL/EO copolymers of Example 1 (triblock diol) and Example 2 (diblock monol). The same performance data on commercial BO/EO materials of similar molecular weight (Examples C-1 and C-2) are also shown in Table 1 for comparison purposes.

wetting, Table I
Foaming and cloud point properties 0.5% 1.0% Ross-Miles foam height (mm)
0.5min 1.0%
25C 0.1%
5OC 1.0%
5OC Turbidity
point
( ⁰ C), Aqu. upper
areas
active Draves wetting time
(lake) 23.5 5.5 0.1%
25C 56.9 11.0 52.0 1.0%
(W/W)
Beginning end Medium 0.1% 14.8 0 37.12 170.18 81.11 171.10 4566 Example 1 >360 14.8 3.7 71.21 23.13 10.0 18.7 79.81 Example C-1 >360 7.8 4.5 25.17 169.33 92.15 158.22 17.22 Example 2 143 91.33 6399 Example C-2 41

• Temperature of analysis was above the cloud point.

Although the wetting performance for the copolyester of Example 1 (i.e., the reaction product of the alkylene oxide, lactone, and initiator) is somewhat lower (longer wetting times) than that for the control block copolymer of Example 1, both are very acceptable from a commercial standpoint. This longer wetting time is likely due to an increased hydrophilic nature of the ε-caprolactone-derived block. The weight percent of oxygen in ε-CL (28.1%) is very similar to that of propylene oxide (27.6%), but BO has 22.2 percent oxygen and a correspondingly lower polarity. The same trend is observed with the two surfactants of Examples 2 and C-2.

The Ross-Miles foaming of the test copolyester polymers is considerably lower than that of commercial BO/EO copolymers. This allows the synthesis of a wide range of copolymer structures with either enhanced or reduced foaming properties, both of which are commercially viable depending on the application.

The cloud point is also affected by the incorporation of ε-CL into the hydrophobic BO. Replacing 17% of the BO in the surfactant of Example C-1 with ε-CL reduces the cloud point by 35 degrees. Replacing 50% of the BO in the surfactant of Example C-2 reduces the cloud point to below room temperature. Incorporating ε-CL into the hydrophobic groups of the block copolymer provides an opportunity to tailor the water solubility of the copolymer to specific commercial requirements.

Tables 2A and B show the results of several measurements made on the βΩ/ε-CL/EO copolyester of Example 1. Also shown are the corresponding data obtained for the commercial triblock of Example C-1. Table 2A shows that the surface and interfacial tension values of 0.1 and 1.0 wt.% are slightly higher for the βΩ/ε-CL/EO copolyester, indicating that there is a lower level of surface activity due to the higher polarity ester functionality. The critical micelle concentrations are not significantly different for each surfactant. It follows that the free energy for micellization is comparable for all.

Table 2A
Interfacial properties of -CL/BO/EO copolyester and a commercial triblock

upper
areas
active
Medium surfaces
tension
(Dynes/cm) 1.0% Interfaces
tension
(Dynes/cm) 1.0% CMC
(molars) CMC
(mg/l) Example 1 0.1% 33.7 0.1% 2.8 2.03E-4 382 Example C-1 34.4 32.4 3.7 2.10E-4 381 32.3 2.3

Table 2B

Surface excess and area per molecule values for -CL/BO-EO copolyester in
Comparison with a commercial triblock

surfaces
excess
(moles/cm ² ) Area
Per
molecule
(Ang2) Delta G
Miz.
(J/mol) C20
(molars) PiCMC
(Dynes/cm) Example 1 1.45 E-10 115 -30,993 1.47E-6 38 Example C-1 1.62E-10 103 -30,916 1.28E-6 40

The values for excess surface concentration and area per molecule in Table 2B indicate that the surfactant copolyester molecules occupy slightly more space at the interface.

Referring again to Table 2B, the C ₂₀ value of the copolyester is higher than that of the BO/EO copolymer, indicating a higher concentration at which interfacial saturation occurs. This value indicates the minimum concentration of surfactant necessary to give a surface tension reduction of 20 dynes/cm.

The effectiveness of a surfactant is defined as the maximum reduction in surface tension that can be obtained at the CMC. This is better described as the maximum surface pressure or Pi _CMC . This value typically evolves as the surfactant efficiency (C ₂₀ ). As can be seen from Table 2, the copolyester has a Pi _CMC value that is 2 dynes/cm lower.

Closedbottle BOD tests were conducted using bacterial germs from an industrial source. The surfactants from Example 2 and C-2 were tested. Dissolved oxygen was measured in replicate samples at 6, 10, 20 and 28 days. These values were used to calculate the percent degradation based on the theoretical value of oxygen that would be consumed if the entire surfactant substrate reacted to yield carbon dioxide and water. Table 3 shows the percent degradation at the indicated time periods. Figure 2 shows the data in graph form. After 28 days, 49% of the copolyester was degraded compared to only 7% of the BO/EO diblock monol control.

Table 3
Biodegradation data from BOD analysis

Connection Theoretical
oxygen
consumption
(mg/l)* Percent degraded surface active
By means of 10· 20. 28· Example C-2 320 6· 3 6 7 Example 2 309 2 28 44 49 14

* based on a concentration of 150 mg/l surfactant
• days

The foam control properties of the above-described ΁Ω/ε-CL random copolymer diols, each having an M _n of approximately 1900, with ε-CLVPO ratios of 20/80 and 50/50 (w/w), were tested using an ASTM standard mixer test D3519-88. The control foam control agent (FCA) was polypropylene glycol P-2000. The results are shown in Figures 3 and 4.

Shown are the initial (t = 0) and final (t = 5 min) foam heights for propylene glycol P-2000 and both �R&Ogr;/ε-CL FCAs at concentrations of 50 and 200 ppm. Also shown are the foam heights of a foaming system without FCA. In each system, �R&Ogr;/ε-CL copolymers controlled the

·

·

Foam more efficient in terms of either initial foam, final foam, or both.

Using the BOD assay described above, Figures 5 and 6 show the results for the 20/80 (w/w) ε-CL/PO FCA and the P-2000 control. Figure 5 shows the results using urban microbes and Figure 6 shows the results using industrial microbes. After 28 days, over 95% of the ε-CL/PO FCA had been degraded in all cases.

The lubricant performance was measured using SRV (oscillation, friction and wear) test equipment to determine the friction coefficient and load carrying capacity of various ε-CL copolymers. The results are summarized in Table 4.

Table 4
Lubricity data for &egr;-CL copolymers

lubricant
(W/W) Friction coefficient
Medium (30 C, 200 N) Extreme pressure mischarge
at 30 C (N) 0.13 KorfRopes* 80/20 &Rgr;&Ogr;/&egr;-CL 0.13 350 50/50 &Rgr;&Ogr;/&egr;-CL 0.11 550 83/17 βΩ/ε-CL 0.13 350

* SYNALOX 50/50B Polyglycol (a polyglycol lubricant manufactured and sold by Dow Chemical Company)

The biodegradable alkylene oxide/e-CL polymers performed favorably compared with the polyglycol control.

Although the invention has been described in detail, the details are for purposes of illustration only, and many changes and modifications may be made by those skilled in the art without departing from the scope of the invention as defined in the following claims.

Claims (1)

Expectations 1. Biodegradable capped alkylene oxide lactone copolymer obtainable by random polymerization of:
A. from an alkylene oxide of the formula R I H-C- R-C-H (D b. derived alkylene oxide units, wherein each R is individually hydrogen, a C ₁ -C ₆ alkyl or alkoxy radical, or wherein two R substituents together with both vicinal epoxy carbons form a saturated or monoethylenically unsaturated cycloaliphatic hydrocarbon ring; and
from a lactone of the formula C=O (II) derived lactone units, wherein η is at least two and each R' is independently hydrogen, C ₁ -C ₄ -A^yI, cyclohexyl, C ₁ -C ₄ -AIkOXy or an aromatic single ring carbon radical; with the proviso that at least four R' are hydrogen; and subsequent capping of the resulting statistical copolymer with a polymer block of polymerized alkylene oxide units derived from an alkylene oxide of the formula (I). Copolymer according to claim 1, wherein the alkylene oxide of formula I is selected from ethylene oxide, propylene oxide and the butylene oxides. A copolymer according to claim 1 or claim 2, wherein the lactone of formula II is an ε-caprolactone . 4. A copolymer according to claim 3, wherein the &egr;-caprolactone has the formula (R") ₂ --cA ⁰ _N . CC-(R") ₂ wherein each R" is independently hydrogen or a C ₁ -C ₄ -alkyl or alkoxy radical, with the proviso that no more than three R" substituents are groups other than hydrogen. 5. The copolymer of claim 4, wherein the ε-caprolactone is an unsubstituted ε-caprolactone. 6. Copolymer according to any one of the preceding claims, wherein the polymer block is derived from polymerized alkylene oxide units in the alkylene oxide cap of ethylene oxide. 7. A process for preparing a biodegradable alkylene oxide-lactone copolymer according to any one of the preceding claims, the process comprising: randomly polymerizing at least one alkylene oxide of formula (I) as defined in claim 1 with at least one lactone of formula (II) as defined in claim 1 and thereafter adding additional alkylene oxide of formula (I) to form a cap. 8. The process according to claim 7, wherein the statistical polymerization is carried out in the presence
a polyfunctional initiator of the formula R ^v (YH)z ' (V) wherein R ^v is an aliphatic, cycloaliphatic, aromatic or heterocyclic radical, ζ is at least two, and each Y is independently -O-, -S-, -NH- or -NR ^Vi -, wherein R ^VI is an alkyl, aryl, aralkyl or cycloalkyl radical, and a catalyst selected from alkali metal hydroxide, alkaline earth metal hydroxides and Lewis acids, in an amount which enables the copolymerization of the alkylene oxide and the lactone. 9. The process of claim 8, wherein the polyfunctional initiator is selected from ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, 1,2-dibutylene glycol, glycerin, trimethylolpropane, pentaerythritol, ethylenediamine and ethanolamine. 10. The process according to claim 9, wherein the catalyst is selected from alkali metal and alkaline earth metal hydroxides. 11. The process of claim 10, wherein the catalyst is potassium hydroxide. 12. Use of a copolymer according to any one of claims 1 to 6 or a copolymer prepared by a process according to any one of claims 7 to 11 as a surfactant, foam control agent or lubricant.